ANALYTICAL STUDY OF GAS UNIT GEOMETRICAL CHARACTERISTICS AND THEIR IMPACT ON THE MOMENTUM OF RECOLILING PARTS

ABSTRACT
On handling the problem of automation in automatic weapons (AW), it is important to
analyze the motion of these weapon mechanisms during their function cycle [1, 2].
Many activities are performed during the backward motion of weapon mechanisms
using the power of branching gases from what known as Gas Unit (GU). These
activities starts with under-slide motion, unlocking, extraction of empty Cartridge
Case (c.c.), backward motion against springs, ejection of empty c.c., and ending by
loading of trigger at the extreme rear position. All these activities are performed in a
reversed manner during the counter recoil track.
In this paper; the parameters affecting the momentum of branching gases have been
extensively studied, the performance of the gas unit is converted to touchable figures
in order to facilitate the evaluation. These evaluations are presented in forms of
change in pressure of gases inside the GU, maximum velocity of recoil, and the
displacement of recoiling parts until the pressure inside the gas unit reaches the
atmospheric value [7,8]. The predicted results determine the weight of each
parameter that affects the momentum of gases. Moreover, the affecting parameters
of GU on the weapon performance during the function cycle may be considered on
modifying the power of in-service weapons, or the newly designed generations